Magnetic pulley



1O produce a magnetic pulley having a high UNITED STATES JOHN P. BETHKE AND ROSWELL H. STEARNS, OF MILWAUKEE, WISCONSIN,

PATENT OFFICE.

ASSIG-NORS r0 MAGNE'IIc MANUFACTURING 00., or MILWAUKEE, w ooNsIN, A CORPORATION OF wIsooNsIN.

'MAGNETIC PULLEY.

To all whom it may concern:

Be it known that we, JOHN P. BETHKE and ROSWELL H. STEARNs, citizens of the United States, residing at Milwaukee, county of Milwaukee, and State of Wisconsin, have invented. new and useful Improvements in Magnetic Pulleys, of which the followlng is a specification.

This invention relates to magnetic pulleys.

One of the objects of this invention is to rate of cooling, or radiation, and having a high flux. density. i v

Other objects are to produce a magnetic pulley in which the interior portions of the pulley are adapted to' have air clrculate therethrough; in which the various openings are intercommunicating to facilitate the C11- culation of air: and in which theinner surfaces are fluted, or ribbed, to resent a greater radiating surface to the clrculatmg Other objects of this invention are to provide a magnetic pulley in which a hlgh current density may be used, thereby producing a magnetic pulley having increased powerand a smaller temperaturerise than has heretofore been possible.

This invention is an improvement upon that disclosed in the earlier application of Roswell H. Stearns for magnetic pulleys, filed Dec. 30, 1919, Serial Number 348,442. The subject matter claimed inthe above identified application is hereby disclaimed.

In the drawing:

Figure 1 is a longitudinal sectional view through the magnetic ulley.- i

Fig. 2 is a view looking downwardly-upon the pulley in the direction indicated at 2-2, in Fig. 1.

Fig. 3 is a sectional elevatlon taken upon the line 3-3 of Fig. 1.

The magnetic pulley comprises a plurality of elements each comprising a core 1 and integrally formed pole flanges 2 which together constitute, in effect, a magnetic spool. Upon this spool is wound the exciting coil 3. The opposed portion of the pole flanges 2 are pIOVlClBd with grooves 4 into which fit the corners of a nonmagnetic protecting rim 5 which closes the spool and protects the winding from injury. The direction of the current in the coils 3, 6 and 7 of the Specification of Letters Patent. Patented A g 16. 1921 Application filed January 22, 1920. Serial No. 353,345.

successive members alternates, that is to say, this current travels in reverse directions 1n adjacent coils, thereby producing consequent poles between the coils. On the outer faces, or ends, of these magnetic spools, concavitles are formed which when two spools are placed together, form an opening8 of materlal size. The ends of the spools are also radially fluted so as to form a large radiatmg surface to facilitate the cooling of the pu leys. The pole pieces 2 are formed upon their outer sides with projiecting lugs 9 which are adapted to-abut thereby forming openmgs 10 between the pulleys along their faces or periphery. These openings 10 communicate with the openings 8 and aid in securing'proper ventilation and cooling of the pulleys. The pulleys are further provided with openmgs 11 (Fig. 3) which extend longitudinally of the pulley and serve to connect the openings 8 to further increase the circulation of air.

In place of the above construction, the

pole pieces 2 may be provided with flanges which abut when the magnetic spools are in'assembled position. These flanges may be subsequently drilled through at 12 which These magnetic pulleys may be bolted to-- gether by through bolts 13 to thereby form a rigid unitary structure, or they may be secured .separately upon the shaft 14 by means of keys. The end portions of the pulley are equipped with non-magnetic flanged rings 15 which prevent material from sticking to the outer pole faces and interfering with the operation of the pulley.

The shaft may be driven by means of a pulley 16 at one end thereof. Upon the other end of the shaft slip rings 17 may be provided which are in. electrical connection with the exciting coils by means of conductors passing through the .conduit 18, 19 formed in. the shaft and through one or more of the pulleys. The wmdings formed on the different pulleys are connect- A upon the pulleys.

It will be seen that a magnetic pulley is produced in which ample radiating surface is provided not only at the ends of the pulley but throughout its entire extent so that the heat from the coil is not stored, nor is it passed on to the next coil, or along the body of the pulley. Each coil is supplied with individual heat radiating means. Further, by the increased radiation, an increased current density may be employed and by this increased current density and by the increased area of magnetic path, free from joints, an increased total flux may be secured.

\Ve claim: 1

1. A magnetic pulley comprising a shaft, a plurality of separate magnetic elements each'independently supported from said shaft, said elements being so related that circulation of air therebetween is secured.

2. A magnetic pulley comprising a plurality of magnetic elements, each element comprising a core, pole flanges extending therefrom, each of said elements having concave fluted ends.

3. A magnetic pulley comprising a plurality of separate magnetic elements, each element comprising a core, diverging flanges extending from the ends of the core, thereby forming a magnetic spool with concave ends, the flanges of adjacent elements conby spaces are formed between adjacentspools by the concavitles.

5. A magnetic pulley having a plurality of elements arranged in axial alinement, each, element comprising a solid magnetic 'spool having a shallow annular groove formed therein, an exciting winding in said groove, and means for separately cooling each element, whereby a high current density may be employed and a large magnetic flux produced.

6. A magnetic pulley comprising a shaft, a plurality of magnetic spools mounted thereon, said spools having adjacent concave ends and a plurality of openings connecting the concavities, thereby providing free circulation of air about each spool.

In testimony whereof we aflix oursignatures in the presence of two witnesses.

JOHN-P. BETHKE. ROSWELL H. STEARNS. Witnesses:

O. C. WEBER, A. R. WOOLFOLK, J r. 

